I am starting my install and have a question about what is the best way to wire it. I am using the standard clarion HU in the boat that has 2 RCA out puts. I am installing 3 amps so should I put a Y connector on one of the RCA out lines, or should I go with a pre amp EQ, or is a cross over an option.

Yes, it's better than using a splitter because the rca out from the amp probably goes through a buffer, or an amplifier stage with a gain of 1. Using a splitter will load the signal from the head unit down a bit, head unit rca outs are generally not designed to supply enough current to run more than one amp. It can impact the SQ.

If you want separate volume controls for the different amps, you might want to also use an EQ as a buffered "splitter" It will give you one more rca out that you can control.

if you use a y splitter, it will burn out the preamp stage of the clarion. it doesn't have the voltage or the impedence capability to do it.

would suggest audiocontrol line driver (line driver or matrix) and add a 3.1 eq if you are running interconects around the other side of the boat~you can modify the sub out to run full range ~ask for dennis@audiocontrol to find out how.

I wanted to go with AudioControl but they did not have a unit with both aux-in, sub out and fading. So I ended up with a cheapo soundstream unit. It works pretty well, Clarion makes a similar unit, plus most other amp manufacurers.

Since Clarions have such low output gain I would definately you add a line driver or EQ. I found the extra control added by the EQ very beneficial in my system.

alot will depend on how high you turn up the volume, length of the interconnects, amp(s) etc....our local nautique dealer has burned out a couple clarion headunits (i have lost a 5 volt eclipse this way)

i really think the audiocontrol gear is more beneficial in a boat than a car - higher power application, longer interconnects,and multiple systems (inside,sub,tower)

you can get a audiocontrol line driver on ebay for $50-$75 or a matrix (multiple) for $100-$125.

the audiocontrol 3.1 and 4.1 will meet the needs when combined with a line driver..

the only other system that can do this is the zapco with symbilink (i am going this route)

if i wasnt i would go the audiocontrol line driver to a audiocontrol 3.1

the MATRIX from Audio Control rocks!!!!! I put in on the boat last night and had to turn the gains on the amps WAY down to keep from overdriving the speakers!!! Spend the few bucks now and do it right!!!!!

Here is how I planned to wire the system. 1 rca out to the ZX850.4 with an pre amp volume control, it will be bridged to power 1 pair of rubicon 350's. I have all monster cable 4 gauge power and ground wire for this amp going directly from the battery to the amp. the other two amps would be attached to the other RCA out either through an EQ or (as some of you suggested a type of audio control box). Using 4 gauge wire to a splitter down to 8 gauge power. the ZX300.1 (might be too small) will power a L5 solo baric. the other ZX650.4 2 channels will power the cabin speakers. The other 2 channels will be bridge to power a single Rubicon 250. Finally the bow speakers will be powered by the HU.

If I was to use a EQ instead of the martix what does everyone suggest? Also what is everyone's opinion on capacitors.

Can I split the single pre-amp output from my head unit to drive two amplifiers with a Y-cable?

YES. When two loads are connected in parallel (such as with a Y-cable) they get the same voltage as each other. They do NOT get the same voltage as if only one load was connected because the head-unit has an internal resistance (typically around 600 ohms). So, given that the amp has a typical input impedance of around 10k ohms then we get something like this:

---See link above for diagram---

for the single amp situation. Please realize that the R(head) and R(amp) are internal to the head unit and amplifier and in fact are not deliberately added resistors but are characteristic of the real world circuits (non-ideal) in the head-unit and amplifier (and eq's, etc.). These numbers are typical, check your specific equipment for its particular specs. the worst case situation is a high source output impedance and low load input impedance.

So, assuming a typical head unit and single amp the voltage seen at the amp (Vamp) is given by (Ohms law/Kirkov's law/1st year EE/high school electronics technology class/etc.):

R(amp) Vamp1 = Vi * ------------------ R(amp) + R(head)

Vamp1 = Vi * 0.94

Now, putting two amps in parallel from the original signal, R(amp) is effectively halved while R(head) is unchanged. Using the same voltage divider formula we get:

10000/2 Vamp2 = Vi * --------------------- 10000/2 + 600

Vamp2 = Vi * 0.89

So, for an Alpine 4V preout, Vi in the diagram (the open circuit head unit line level output) is 4V. Thus Vamp1 = 3.76V and Vamp2 = 3.56V. With two amplifiers' inputs connected in parallel, the voltage is reduced from 3.76V to 3.56V or approximately 5%, not a big deal.

If you had a more typical 1V preout you would get Vamp1 = 0.95V and Vamp2 = .89V, also not a noticeable drop.

This is also why this is slightly more susceptible to noise than a direct one-to-one connection. If the noise level inserted due to cabling was 0.1V per cable then the noise level in the signal reaching each of the two amps would be a slightly higher percent of the signal level but not doubled. (this is also why the 4V head unit is favored over the 1V unit for noise immunity: 0.1V noise / 3.76V or 3% is much less than 0.1V noise / 0.95V or 10% even in a one to one connection).

That calc is for straight DC resistance, not AC impedance, so it is BS. If you go nuts with ohms law or measure it with a scope you'll find that a 4v output is actually 2.9vac. That is the max that can be produced using rail to rail op amps used in modern head units that do NOT have a switching supply (everything except Eclipse) And, when you run them into twice the load (half the ohms) they supply less AC voltage. The "resistors" or internal impedances used in that calc are not static values, they change with frequency. On paper, you can use splitters but like Mike said, you might fry the cheesy opamp output circuit in some head units. The head might not be able to supply enough current to keep the voltage up there like that post says, especially during peaks or long duty cycle (subwoofer output). So, at best you get distortion which sounds like poopie, or worst case a burnt op amp and junque head unit. Good thing is, you can probably find out how to repair head units on Wikipedia.

Or use a line driver. I recommend the Planet Audio PLD6, which you can get on Ebay for 40$. It is similar to the Matrix, 6 channel. They are a closeout or something so they are super cheap. I put one on the bench and burned it in to make sure it would hold up before I put it in my boat. It is a quality piece, and you can buy 4 for the price of 1 AC Matrix. It is big, it's the size of an amp.

psyclone hit the nail on the head btw,great PAC modifacation on the other thread

"And, when you run them into twice the load (half the ohms) they supply less AC voltage"

the preamp stage is just like a power amp - split the signal=drop the impedence and in the case of most decks lower voltage out..and in case of the passive units, the impedence is dependant on the position of the volume. this is a overlooked stage in most car stereo's and way overlooked in marine audio..it take a high voltage low impedence deck to run lllloooonnnngggggg cables..

greg - kinda of a tough call...if it was "me" a non zapco/symblink solution be be 2 units..one to get the signal there (basic audiocontrol line drive with 1 set of rca's to a 3.1 eq (3 sets of rca's on return)

the 3.1 has 2 volume controls and a fader..btw, the sub control crossover can be set to run full range mixed signal which is is perfect for tower speakers.. so that would give you inside the boat volume control, fader for front back and using the sub volume for the tower volume..

the audiocontrol line drivers go for $40(used) $100 (new) and the 3.1 between $110(used)-$185(new).

hope that helps...

btw, a incredible interconnect is the audio art ic1 cable would at least use 1 pair between the head unit to driver and the longer lengths if you can.. website is audioart.com

btw, would it make sense to use a single line driver between the ipod outs to the deck aux input?

I think it would take less strain of the amps (running a .5~.75mv signal into a 2 volt deck then to a line driver then through 40 feet of interconnect ) and should make mp3 listening a heck of a lot better.

Just wanted to say thanks for all your help. I ended up going with a Audiocontrol EQS it has a built in line driver. I also installed a pre amp Alpine volume control. I worked on it all day today and I should be done tomorrow. I will post pic of the install when complete. Thanks again.